Re-analyzing the Physical Causes for Destruction in the World Trade Center on 9/11

The prevailing analyses that have been made using mechanical models for gravitational collapses of the buildings of the World Trade Center are shown to generally have physical aws or inadequacies. This includes those in the Reports (about 45) published by the National Institute of Standards and Technology (NIST) Committee of the United States on the World Trade Center (WTC) collapses. These physical aws can fall into 3 dierent categories. The rst is disagreement with known principles of physics, such as conservation of energy and momentum. The second is important factual discrepancies with observa-tions on how the collapses occurred. This includes ignoring horizontal forces, and modelling the collapses with a "crush-up " phase, for which there is no evi-dence. The third is oversimplied assumptions, which create inadequacy of the physical model in describing the collapse. The third physical aw particularly regards eorts to use 1D models for the collapses, which ignores important 3D eects for the stability of the Towers, as well as signicant horizontal motion that is observed. These analyses are examined, with eorts to point out these physical aws and limitations of model solutions, as well as their implications. Discussion is made of what the ignored eects show and suggest as the causes, and the multiple rectications needed in analyzing the collapses before mechan-ical modelling can provide correct insight into how the Towers and Building 7 fell. Scienti c Analysis of the World Trade Center Col-lapses Most of us remember that fateful day on September 11, 2001, when the World Trade Center Towers (WTC) in New York City were attacked by terrorists with plane collisions. Several scientic analyses have been developed since to try to explain how the North and South Towers collapsed.[1] Bazant and Zhou developed a simple model in 2002 for the Towers collapses called the "crush-down, crush-up " model [1]. In this model gravitational collapse initiates at some height along the tower, cascades into successive collapses at lower and lower points on the tower ("crushing-down"), and continues until the point where the building material at the location of the collaps